CVE-2026-31787

In the Linux kernel, the following vulnerability has been resolved: xen/privcmd: fix double free via VMA splitting privcmd_vm_ops defines .close (privcmd_close), but neither .may_split nor .open. When userspace does a partial munmap() on a privcmd mapping, the kernel splits the VMA via __split_vma(). Since may_split is NULL, the split is allowed. vm_area_dup() copies vm_private_data (a pages array allocated in alloc_empty_pages()) into the new VMA without any fixup, because there is no .open callback. Both VMAs now point to the same pages array. When the unmapped portion is closed, privcmd_close() calls: - xen_unmap_domain_gfn_range() - xen_free_unpopulated_pages() - kvfree(pages) The surviving VMA still holds the dangling pointer. When it is later destroyed, the same sequence runs again, which leads to a double free. Fix this issue by adding a .may_split callback denying the VMA split. This is XSA-487 / CVE-2026-31787

• linux linux kernel (>= 3.8 < 5.10.254) • linux linux kernel (>= 5.11 < 5.15.204) • linux linux kernel (>= 5.16 < 6.1.170) • linux linux kernel (>= 6.2 < 6.6.137) • linux linux kernel (>= 6.7 < 6.12.85) • linux linux kernel (>= 6.13 < 6.18.26) • linux linux kernel (>= 6.19 < 7.0.3) • linux linux kernel 7.1